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Reduced basal levels and enhanced LPS response of IL-6 mRNA in aged mice
K Sharman1, E Sharman, A Campbell
1Center for Occupational and Environmental Health, Department of Community and Environmental Medicine, University of California, Irvine, CA 92697-1825, USA.
Abstract:
Senescence is a complex and multifactorial process that may predispose organisms to altered responses to environmental stressors. The cytokine interleukin-6 (IL-6) is expressed by a variety of cells and is one of the earliest mediators of the acute inflammatory response. In this study, the level of IL-6 mRNA in younger (7 months) and old (23 months) mice was determined in the tissue of several organs with or without stimulation with lipopolysaccharide (LPS). Whereas younger animals had a basal expression of IL-6 mRNA in all organs, this was undetectable in the old animals. In contrast, when the mice were injected with LPS, in a majority of the organ tissues there was a robust stimulation of IL-6 mRNA in the old mice whereas the younger animals had a more variable response. These data indicate that the aging process may predispose animals to an exaggerated and potentially harmful inflammatory response.
Insights
Aging alters inflammatory responses, leading to exaggerated reactions to stressors. Old mice showed significantly higher interleukin-6 (IL-6) mRNA levels after lipopolysaccharide (LPS) stimulation compared to younger mice.
Area of Science:
- Immunology
- Gerontology
- Molecular Biology
Background:
- Cellular senescence is a complex process impacting organismal responses to environmental challenges.
- Interleukin-6 (IL-6) is a key cytokine mediating early inflammatory responses.
Purpose of the Study:
- To investigate age-related differences in IL-6 mRNA expression in response to lipopolysaccharide (LPS) stimulation.
- To determine if senescence influences the inflammatory mediator IL-6.
Main Methods:
- Quantified IL-6 mRNA levels in various organs of young (7-month-old) and old (23-month-old) mice.
- Compared IL-6 mRNA expression with and without LPS stimulation.
Main Results:
- Young mice exhibited basal IL-6 mRNA expression across organs.
- Old mice showed undetectable basal IL-6 mRNA but a robust response upon LPS stimulation in most organs.
- Young mice displayed a variable IL-6 mRNA response to LPS.
Conclusions:
- The aging process can lead to an exaggerated inflammatory response.
- Age-related changes in IL-6 regulation may contribute to increased susceptibility to inflammatory damage.